In recent months the conventional blowing agents, the fluorochlorocarbons, e.g., fluorocarbon 11, have come under attack from environmentalists. The urethane foam industry which has had such good results using these agents has had to turn to other blowing agents to supplant all or part of the conventional fluorocarbons, e.g., fluorocarbon F-11. The logical choice was methylene chloride, a blowing agent which has been used by industry on a selective basis at lower levels in the past. The urethane foam industry found that methylene chloride was not a suitable blowing agent at higher levels because it required excessive amounts of gellation catalysts to fix the urethane in its risen or foam state prior to final cure and that these increased amounts of gellation agent reduced processing latitude. The practice today is to use a co-blowing agent with the methylene chloride or accept the requirement that large amounts of the gelling catalyst are required. As a result the industry has used the methylene chloride sparingly.
It is an object of the present invention to provide a means enabling the use of methylene chloride as the sole agent to replace the fluorohalohydrocarbons and to reduce the amount of the gelling catalyst required to obtain stability in the foam until curing can occur when using the methylene chloride.